Living radical polymerization is a polymerization technique that enables precise control of molecular structures while maintaining the convenience and versatility of radical polymerization, and makes a significant contribution to the syntheses of novel polymeric materials.
The inventors have reported, as an example of living radical polymerization, a living radical polymerization method using an organobismuth compound as an initiator (see for example Patent Document 1).
[Patent Document 1] WO 2006/62255
The method in Patent Document 1 makes it possible to control molecular weights and molecular weight distributions. However, in preparing high-molecular weight polymers having a number average molecular weight of 100000 or more, their molecular weight distributions may be wider than, but not more than 1.5, those of low-molecular weight polymers.
A purpose of the present invention is to provide a living radical polymerization promoter that enables precise control of the molecular weight and molecular weight distribution (PDI=Mw/Mn) of even a high-molecular weight polymer having a number average molecular weight of 100000 or more by polymerizing a vinyl monomer using an organobismuth compound represented by the formula (1) as the living radical polymerization promoter.